Research in the Needleman laboratory combines physics and cell biology to study self-organizing subcellular structures. Our long term goals are to uncover general principles which govern these nonequilibrium systems and to develop predictive theories of cellular organization and behavior. Our approach is to study complex biological systems using a close interplay between quantitative experiments and theory, developing new methods to produce the data we need. Our research focuses on the spindle, the self-organized structure that segregates chromosomes during cell division. Recent advances have led to a nearly complete molecular “parts lists” of the spindle, but it remains poorly understood how spindle structure and function arise from these constituents. We are bridging the molecular scales, of nanometers and milliseconds, and the cellular scales, of microns and minutes, by investigating collective mechanics and energetics in spindles. We also study how these collective properties vary over evolution and due to non-genetic factors: to understand the process that shape variations in spindles and to use these variations to obtain increased mechanistic insights. In recent work, we have expanded to study embryology, and basic and applied issues related to in vitro fertilization.